Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$184.75	8.514%	$200.4796	$200.48	$200.50	$200.50
Purchase #2	$24.61	3.173%	$25.3909	$25.39	$25.40	$25.40
Purchase #3	$153.94	11.526%	$171.6831	$171.68	$171.70	$171.70
Purchase #4	$186.27	5.454%	$196.4292	$196.43	$196.45	$196.40
Purchase #5	$44.38	10.346%	$48.9716	$48.97	$48.95	$49.00
Purchase #6	$96.28	9.194%	$105.132	$105.13	$105.15	$105.10
Purchase #7	$60.51	6.493%	$64.4389	$64.44	$64.45	$64.40
7 purchase totals =	$750.74		$812.5253	$812.52	$812.60	$812.50